The present invention provides an integration and analog to digital conversion circuit sharing common capacitors. The circuit comprises a first capacitor array module, a second capacitor module, an integration circuit, an analog to digital conversion (ADC) logic. The first capacitor array module has a plurality of capacitors. The second capacitor array module has a plurality of capacitors. The integration circuit is configured to integrate an analog signal by said first or said second capacitor array module. The ADC logic is configured to convert the output of said first or said second capacitor array module to a digital signal. The ADC logic performs conversion by said first capacitor array module while said integration circuit performs integration by said second capacitor array module, and said ADC logic performs conversion by said second capacitor array module while said integration circuit performs integration by said first capacitor array module.